package com.blue.alipay.utils.sign;

import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

public class RSA {

	private static final String SIGN_ALGORITHMS = "SHA1WithRSA";
	
	/**
	* RSA签名
	* @param content 待签名数据
	* @param privateKey 商户私钥
	* @param inputCharset 编码格式
	* @return 签名值
	*/
	public static String sign(String content, String privateKey, String inputCharset) {
		try {
			PKCS8EncodedKeySpec priPKCS8 	= new PKCS8EncodedKeySpec( Base64.decode(privateKey) ); 
        	KeyFactory keyf 				= KeyFactory.getInstance("RSA");
        	PrivateKey priKey 				= keyf.generatePrivate(priPKCS8);

			java.security.Signature signature = java.security.Signature.getInstance(SIGN_ALGORITHMS);
			signature.initSign(priKey);
			signature.update(content.getBytes(inputCharset));
			byte[] signed = signature.sign();
			return Base64.encode(signed);
		} catch (Exception e) {
			e.printStackTrace();
		}

		return null;
	}

	/**
	* RSA验签名检查
	* @param content 待签名数据
	* @param sign 签名值
	* @param publicKey 支付宝公钥
	* @param inputCharset 编码格式
	* @return 布尔值
	*/
	public static boolean verify(String content, String sign, String publicKey, String inputCharset) {
		try {
			KeyFactory keyFactory = KeyFactory.getInstance("RSA");
			byte[] encodedKey = Base64.decode(publicKey);
			PublicKey pubKey = keyFactory.generatePublic(new X509EncodedKeySpec(encodedKey));

			java.security.Signature signature = java.security.Signature.getInstance(SIGN_ALGORITHMS);
			signature.initVerify(pubKey);
			signature.update(content.getBytes(inputCharset));
			return signature.verify(Base64.decode(sign));

		} catch (Exception e) {
			e.printStackTrace();
		}

		return false;
	}

}
